Pivot assembly

ABSTRACT

A pivot assembly has a pivot support member with a keyway. The keyway has two oppositely directed longer keyway wings extending from a middle section and the middle section has two oppositely directed shorter keyway wings extending in a direction transverse to that of the longer keyway wings. The shorter keyway wings have convexly radiused ends. The pivot assembly also has a pivot with an attachment portion and a key projecting rearwardly from the attachment portion. The key has a rearward section with oppositely directed longer key wings which are longer than the shorter keyway wings but sufficiently short to allow the longer key wings to pass through the keyway. The key also has a middle section between the rearward section and the attachment portion. The middle section has oppositely directed shorter key wings with convexly radiused ends. The shorter key wings extend in a direction aligned with that of the longer key wings. The shorter key wings have a length substantially matching that of a length of the shorter keyway wings. The radiused end of each shorter key wing has a radius substantially matching a radius of a radiused end of each of the shorter keyway wings such that the shorter key wings fit with a close tolerance between ends of the keyway shorter wings.

BACKGROUND

This invention relates to a pivot assembly and to a chair control incorporating a pivot assembly.

It is known to slidably mount a slide plate to the seat plate of a chair control to allow the user to change the relative position of a chair seat, which is attached to the slide plate, to the seat plate. In a known arrangement, a U-shaped member is pivotably mounted to either side of the slide plate with the free ends of the U-shaped member received in racks which form part of the seat plate. The U-shaped member is spring biased so that the free ends are urged into the racks, thereby fixing the relative position of the slide plate and seat plate. If the U-shaped member is pivoted by a user against this spring pressure, the free ends leave the racks, freeing the slide plate to slide with respect to the seat plate. When a desired position is achieved, the U-shaped member may be released whereupon the free ends of the member will re-enter the racks and lock the slide plate in this new relative position with respect to the seat plate.

The U-shaped member is pivotably mounted to the slide plate by a pair of pivots, each of which has an attachment portion which attaches to the U-shaped member. A pop rivet may be received through a hole in a pivot and through the slide plate in order to pivotably affix the pivot to the slide plate.

This invention seeks to provide an improved pivot assembly.

SUMMARY OF INVENTION

In accordance with this invention, there is provided a pivot assembly with a pivot support member having a keyway. The keyway has two oppositely directed longer keyway wings extending from a middle section and the middle section has two oppositely directed shorter keyway wings extending in a direction transverse to that of the longer keyway wings. The shorter keyway wings have convexly radiused ends. The pivot assembly also has a pivot with an attachment portion and a key projecting rearwardly from the attachment portion. The key has a rearward section with oppositely directed longer key wings which are longer than the shorter keyway wings but sufficiently short to allow the longer key wings to pass through the keyway. The key also has a middle section between the rearward section and the attachment portion. The middle section has oppositely directed shorter key wings with convexly radiused ends. The shorter key wings extend in a direction aligned with that of the longer key wings. The shorter key wings have a length substantially matching that of a length of the shorter keyway wings. The radiused end of each shorter key wing has a radius substantially matching a radius of a radiused end of each of the shorter keyway wings such that the shorter key wings fit with a close tolerance between ends of the keyway shorter wings.

Other features and advantages will be apparent from the following description in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the figures which illustrate an example embodiment of the invention,

FIG. 1 is a perspective view of a chair control,

FIG. 2 is a partially assembled fragmentary perspective view of the chair control of FIG. 1,

FIG. 2A is a fragmentary side view of a portion of FIG. 2,

FIG. 2B is a side view of a portion of FIG. 2,

FIG. 3A is a partially assembled fragmentary perspective view of the chair control of FIG. 1,

FIG. 3B is a cross-sectional view along the lines 3B-3B of FIG. 3,

FIG. 4A is a partially assembled fragmentary perspective view of the chair control of FIG. 1,

FIG. 4B is a cross-sectional view along the lines 4B-4B of FIG. 4,

FIG. 5 is a partially exploded perspective view of the chair control of FIG. 1,

FIGS. 6A to 6E are schematic side views of the chair control of FIG. 1 illustrating its operation.

DETAILED DESCRIPTION

Referring to FIGS. 1 and 6B, a chair control 10 has a slide plate 12 with aligned longitudinal slots 14 receiving bolts 16 that are screwed to a seat plate 20. This provides a sliding attachment of the slide plate to the seat plate. A chair seat 18 (FIG. 6A) may be attached to the slide plate. The seat plate 20 may be pivotably mounted to the main frame 21 of the chair and the main frame 21 may be supported on a gas cylinder (not shown) extending from a chair base (not shown). A U-shaped member 22 is joined to the sides 24, 26 of the slide plate 12 by pivots 30. The U-shaped member has arms 68 terminating in inwardly turned free ends 32, each of which extends through a slot 34 in the slide plate and terminates at a rack 36 attached to the seat plate. The medial section of the U-shaped member 22 forms a handle 38. A spring 40 coils around each free end 32 and has its ends supported by catches 42 formed in the slide plate. These springs bias the U-shaped member so that the free ends 32 are urged into racks 36.

With reference to FIGS. 2 and 2A, the slide plate 12 has a keyway 50 formed in each of its sides 24, 26. The keyway has two oppositely directed longer keyway wings 52 a, 52 b extending from a middle section formed by two oppositely directed shorter keyway wings 54 a, 54 b. As is apparent from the figures, the shorter keyway wings extend in a direction transverse to that of the longer keyway wings. The shorter keyway wings 54 a, 54 b have radiused ends 56 a, 56 b.

Referencing FIGS. 2 and 2B, each pivot 30 has an attachment portion 58 with a key 60 projecting rearwardly from the attachment portion. The key has a rearward section, R, with oppositely directed longer key wings 62 a, 62 b. The key also has a middle section, M, between the rearward section and the attachment portion. The middle section has a thickness slightly greater than that of the thickness of the slide plate 12. The middle section has oppositely directed shorter key wings 64 a, 64 b. The shorter key wings 64 a, 64 b extend in a direction aligned with that of the longer key wings 62 a, 62 b. The longer key wings 62 a, 62 b are longer than the shorter keyway wings 54 a, 54 b and shorter than the longer keyway wings 52 a, 52 b. The shorter key wings 64 a, 64 b have a length substantially matching that of a length of the shorter keyway wings 54 a, 54 b and each shorter key wing has a radiused end 66 a, 66 b with a radius substantially matching a radius of the radiused end of each of said shorter keyway wings 54 a, 54 b.

The attachment portion 58 of each pivot 30 is C-shaped with the central axis of the C-shape aligned with the direction of the longer key wings 62 a, 62 b. An arm 68 of the U-shaped member 22 may snap into the attachment section.

With reference to FIG. 2, the pivot 30 may be oriented so that the longer key wings 62 a, 62 b are aligned with the longer keyway wings 52 a, 52 b and the longer key wings 62 a, 62 b may then be passed through keyway 50 as shown in FIGS. 3A and 3B until areas of the rearward surface of the attachment portion 58 that extend outside the periphery of the keyway abut the slide plate 12. In this position, the longer key wings 62 a, 62 b are located behind the back face of the side of the slide plate. Next, as shown in FIGS. 4A and 4B, the pivot 30 may be turned 90° so that the longer key wings 62 a, 62 b are now aligned with the shorter keyway wings 54 a, 54 b. Thus, the side wall of the slide plate is sandwiched between the longer key wings 62 a, 62 b of the pivot and the rear surface of the attachment portion 58 of the pivot. Consequently, the pivot is locked to the side wall. Further, the shorter key wings 64 a, 64 b are now located in the keyway and are aligned with the shorter keyway wings 54 a, 54 b with the radiused ends 66 a, 66 b of these wings snugly fitted against the radiused ends 56 a, 56 b of the shorter keyway wings 54 a, 54 b.

Pivot 30 may be pivoted through a range of angles (of about +/−30°) from its position as shown in FIG. 4A while an arcuate segment of each of the shorter key wings 64 a, 64 b remains snugly fitted against the radiused ends 56 a, 56 b of the shorter keyway wings 54 a, 54 b and the slide plate side wall remains sandwiched between the longer key wings 62 a, 62 b and the rear surface of the attachment portion 58. Thus, within this range of motion, the pivot will remain securely locked to the side wall.

Prior to attaching a pivot 30 to each of side wall 24 and 26 of the slide plate, each pivot may be snapped onto an arm 68 of the U-shaped member 22 and a spring 40 may be run over each arm. As the pivots are pivoted toward the position indicated by FIG. 4, the free ends 32 of the U-shaped member may be deflected outwardly to allow the U-shaped member to pivot until these ends 32 pop into the slots 34 in the side walls of the slide plate. With the ends 32 within slots 34, the range of pivoting motion of the U-shaped member is limited by the abutment of the ends 32 with the ends of the slots 34. This range of motion is selected so that the pivots remain securely locked to the side wall throughout this range of motion. The ends of the springs may then be inserted into catches 42 to bias the ends 32 of the U-shaped member into the racks attached to the seat plate 20. Lastly, as shown in FIG. 5, a cap 70 may be snap fit to each pivot 30.

The pivot is of one piece construction and manufactured from a hard plastic.

Operation of the chair control 10 is illustrated in FIGS. 6A to 6E. With the U-shaped member in a slide plate locking position (FIG. 6A) whereat the free ends 32 of the U-shaped member are received in the racks of the seat plate, a user may lift handle 38 (FIG. 6B). This rotates the U-shaped member against the urging of the springs 40 so that the ends 32 of the U-shaped member leave the racks and abut the lower end of the slots 34 (FIG. 6C). The slide plate may then be slid to any desired position. Thereafter, the handle 38 may be released so that the U-shaped member rotates back to its slide plate locking position (FIGS. 6D and 6E). (In this regard, the nose of each tooth of the racks may be radiused so that if each end 32 hits a tooth, the slide plate would move slightly to align each end 32 with a notch between rack teeth.)

The described pivot assembly avoids the need for a separate fastener (such as a pop rivet) to hold the pivot to the slide plate. This therefore simplifies manufacturing.

Of course the pivot could be constructed of metal rather than plastic. The longer wings of the keyway and key of the pivot need not have radiused ends but could, if desired, instead have ends which are squared off. The attachment portion of the pivot need not be a resilient clip but could instead be any other suitable attachment device, such as a two-piece housing which is held together with a snap fit or fasteners.

The described pivot assembly could be used in other pivoting applications where the range of pivoting is limited. Further, in applications where the pivot may be tilted when it is inserted into the keyway, the longer key wings could be longer than the longer keyway wings. (The limit to the length of the longer keyway wings would be that where, after the upper longer key wing is inserted through the keyway at a tilt angle and the pivot raised until its middle section abuts the end of the upper longer keyway wing, there is just enough space for the lower longer key wing to pass through the lower longer keyway wing.)

Other modifications will be apparent to those skilled in the art and, therefore, the invention is defined in the claims. 

1. A pivot assembly comprising: a pivot support member having a keyway, said keyway having two oppositely directed longer keyway wings extending from a middle section, said middle section having two oppositely directed shorter keyway wings extending in a direction transverse to that of said longer keyway wings, said shorter keyway wings having convexly radiused ends; and a pivot having an attachment portion and a key projecting rearwardly from said attachment portion, said key having a rearward section with oppositely directed longer key wings which are longer than said shorter keyway wings but sufficiently short to allow said longer key wings to pass through said keyway and a middle section between said rearward section and said attachment portion, said middle section having oppositely directed shorter key wings having convexly radiused ends, said shorter key wings extending in a direction aligned with that of said longer key wings, said shorter key wings having a length substantially matching that of a length of said shorter keyway wings and each shorter key wing radiused end having a radius substantially matching a radius of a radiused end of each of said shorter keyway wings such that said shorter key wings fit with a close tolerance between ends of said keyway shorter wings.
 2. The pivot assembly of claim 1 wherein said pivot support has a thickness substantially matching a thickness of said middle section of said pivot.
 3. The pivot assembly of claim 2 wherein said pivot is of one piece construction.
 4. The pivot assembly of claim 3 wherein said pivot is fabricated of plastic.
 5. The pivot assembly of claim 1 wherein said attachment portion of said pivot comprises a resilient C-shaped clip.
 6. The pivot assembly of claim 5 wherein a central axis of said C-shaped clip is aligned with a direction of said longer key wings.
 7. The pivot assembly of claim 1 wherein said longer key wings are shorter than said longer keyway wings.
 8. A pivot comprising: an attachment portion comprising a resilient C-shaped clip; a key projecting rearwardly from said attachment portion, said key having a rearward section with oppositely directed longer key wings and a middle section between said attachment portion and said rearward section, said middle section having oppositely directed shorter key wings having convexly radiused ends, said shorter key wings extending in a direction aligned with that of said longer key wings, a central axis of said C-shaped clip being aligned with a direction of said longer key wings.
 9. A chair control, comprising: a slide plate having a keyway, said keyway having two oppositely directed longer keyway wings extending from a middle section, said middle section having two oppositely directed shorter keyway wings extending in a direction transverse to that of said longer keyway wings, said shorter keyway wings having convexly radiused ends; and a pivot having an attachment portion and a key projecting rearwardly from said attachment portion, said key having a rearward section with oppositely directed longer key wings which are longer than said shorter keyway wings but sufficiently short to allow said longer key wings to pass through said keyway and a middle section between said rearward section and said attachment portion, said middle section having oppositely directed shorter key wings having convexly radiused ends, said shorter key wings extending in a direction aligned with that of said longer key wings, said shorter key wings having a length substantially matching that of a length of said shorter keyway wings and each shorter key wing radiused end having a radius substantially matching a radius of a radiused end of each of said shorter keyway wings, said shorter key wings fit between ends of said keyway shorter wings.
 10. The chair control of claim 9 wherein said slide plate has a thickness substantially matching a thickness of said middle section.
 11. The chair control of claim 10, wherein said pivot is of one piece construction.
 12. The chair control of claim 11 wherein said pivot is fabricated of plastic.
 13. The chair control of claim 10 further comprising an arm attached to said attachment portion of said pivot, said arm terminating in a free end received in a slot of said slide plate such that rotation of said arm at said pivot is limited.
 14. The chair control of claim 13 wherein said attachment portion of said pivot comprises a resilient C-shaped clip.
 15. The chair control of claim 14 wherein a central axis of said C-shaped clip is aligned with a direction of said longer key wings.
 16. The chair control of claim 9 wherein said longer key wings are shorter than said longer keyway wings. 